Extensive Scaling on a Live HardwoodPosted: May 27, 2013
I suspect that bark scaling like this (on a moribund but still live tree) is diagnostic for Ivory-billed Woodpecker.
The bark is uniformly tight and has been peeled off cleanly. The underlying wood is unexcavated. The edges of the scaled areas show no sign that the bark was removed in layers. Many chips/chunks of bark found at the base of this tree match Tanner’s description for tight bark scaling: ‘between the size of a silver dollar and that of a man’s hand’, and between a quarter and half an inch thick. They were still moist when found week before last.
When Pileated Woodpeckers extensively scale tight bark (and often looser bark as well), they remove it in layers. The photograph below is of presumed PIWO scaling on a cherry in Illinois. Cherry bark is thin and tends to slough off naturally. Even so, some of the edges of the scaled areas show clear signs that the bark has been removed in layers, note the upper left edge in particular . The chips found under this tree were small and thin. This is because Pileated Woodpecker anatomy – foot and bill structure – limits the ability to remove bark with lateral blows, as Campephilus woodpeckers do. The chips themselves, while sometimes long are more like flakes or strips than chunks. Indication of removal in layers is visible on some of them.
The images in this blog post further illustrate how inefficiently Pileateds scale on denser-barked hardwoods.
I’ve tried to track down examples of scaling by Campephilus woodpeckers online, and it’s hard to find many good ones. The following links are the best I could find.
While it’s in a close up and therefore possibly misleading, the Crimson-crested Woodpecker scaling looks closest to what I suspect to be diagnostic for ivorybill. Some of the other work lacks the clean edges and incision all the way down to the cambium, and is more similar to Pileated work than the narrow category of work I believe to be distinguishable as ivorybill.
We have placed a Reconyx camera on the tree, and it is taking a photograph every 20 seconds. Thus far, we have documented a Hairy Woodpecker removing a small rectangular patch of bark. While the edges are clean, the time it takes a Hairy Woodpecker to scale a few square inches and the size of the chips involved rule that species out as the source of the more extensive scaling. We have also documented a Pileated Woodpecker on the trunk but not engaging in any scaling whatsoever.
Updated: I’m posting the two Reconyx series, which were taken approximately 20 minutes apart. It takes the Hairy Woodpecker 4 minutes to remove a small rectangular patch of bark. The Pileated arrives 20 minutes after the Hairy departs. As Frank Wiley pointed out in an email that accompanied these images, it’s interesting to note that the Pileated appears to be examining the patch scaled by the Hairy. The sequence also makes it clear that the Pileated does not do any scaling; when on the far side of the tree, it is face on to the camera, not positioned in a way that’s consistent with scaling, and no bark is removed on the part of the tree that’s facing the camera. These are the only hits we’ve had over several days of coverage and Frank has gone through thousands of images thus far.